You make a good point, Now if I could just know in May & June what they would look like in the fall I could possibly pick more? Guess it still comes down to Trail and Error.I start letting them go once June swings around. They need to be growing in the summer so they can start storing energy in their roots for next year.
It's a bit of a trick learning how much you can pick. When you're in the fall look at how much fern you have. If it's a big thick wad of fern that's not getting much light then you didn't pick enough.